1. Field of the Invention
The present invention relates to a system for automatically producing different semiconductor products in different quantities through a plurality of processes along a production line. Before starting actual production, the system automatically simulates the characteristics and reliability of products, to prepare a process flow containing optimum process conditions for producing best products. The system evaluates and analyzes the products actually produced and the simulation results, and according to results of the evaluation and analysis, improves simulation accuracy.
2. Description of the Prior Art
Generally speaking, in semiconductor manufacturing, there is provided information representing a series of process flow steps (process flow information) based upon which the production of a semiconductor device is controlled. This information is prepared by presuming at the discretion of technical experts completeness of a product based upon their experience or know-how. In this case, since it is extremely difficult for the technical experts to devote all their time to decide the process conditions, the undefined process conditions have beforehand been set on many divergences and the product has dividually been produced at actually processing the product. Therefore, it takes a great deal of time to carry out dividing/combining operations for the products, the data analysis after the operations are completed, or the like, so that the time required for manufacturing the product has been prolonged.
Moreover, in the case where the process conditions are presumed, a process/equipment simulator or a simulation such as a circuit simulator or the like has been used. In such a simulator feedbacks of the simulation results and the process conditions to the process flow are conducted according to a judgement of the technical expert, and consequently it has been impossible to correct the feedbacks by differences between individuals and to perform appropriate feedbacks.
Moreover, after the process flow is decided, the products are actually manufactured, and they are completed, the analysis on an electrical characteristic or data of reliability has been carried out by the technical experts, and in the case where any product is delinquent, the information of the processed process flow has been analyzed one by one, alternatively it has so far been judged from a viewpoint of the experience of the technical experts and analyzed. Moreover, since it is difficult that the results of the actually manufactured product is performed the feedbacks to the simulation or the like, it is difficult to enhance precision of the simulation.
In this manner, in the conventional semiconductor manufacturing techniques, it is difficult to provide exchange of information between the process flow information and various simulations or a production system.
Therefore, a manufacturing process has increased in an assignment of the process conditions, the divisions of the product, or the like, and therefore the time of process has been prolonged. Moreover, it is difficult to skillfully fetch the calculation results derived from various simulation into the process flow, and furthermore it is difficult to carry out the inferior analysis of the product and enhance the precision of the simulation itself by comparing the results of the completed produce with those of the simulation.
Next, in a stage of the above-mentioned process flow preparation, various simulations, checks, and verifications are carried out. With such the execution, the conventional drawbacks in the course of various processes will be described hereinafter.
First, in the initial process flow preparation of the prior art, a process flow sheet for controlling a product flow line is composed of several figures of alphanumeric "process codes", a process title, and the contents. The product flow line generally constitutes a series of a plurality of processes and the individual process is sequence-processed to manufacture a product from an original material.
Conventionally, such a series of process flow steps has been described on the basis of several figures of alphanumeric codes called the above-mentioned "process codes".
The process codes have a preferred format such that one code corresponds to one process and a great amount of information such as the process conditions, the contents, or the like is annexed to these codes. For instance, citing as a sample the codes for use in a semiconductor manufacturing line in order to comment on these codes, "process code=R01" was secured to "buffer oxidized gas (oxygen) temperature (900.degree. C.) time (20 min.)".
Such codes are annexed to every process existing in the manufacturing line, which is controlled according to table of values describing a corresponding relationship between the codes and the process contents. Also, the number of codes may be several thousands.
Using such a table of values corresponding the abovementioned codes to the process contents, the technical experts have been able to prepare process flow sheet along with the manufacturing process flow each process by handwriting, or making use of a word processor, a screen editor, or the like.
Accordingly, in the above-mentioned prior art, when the kind of process increases in the manufacturing process line, the number of the process code also increases concurrently. In the case where the technical experts described the process flow in such a code management, there were caused such drawbacks that it became difficult to pick out the codes and that it became very difficult to describe the manufacturing process flow.
Moreover, there were also caused such drawbacks that an incorrect spelling of the codes, a mistake in a describing format, or the like was provoked in the handwriting method, the word processor, or the screen editor, therefore it took a great amount of time to describe the manufacturing process flow.
Next, in the simulation process of the process flow, the process flow information for use in the manufacturing line has conventionally had a format which is completely different from that of the process flow information for use in the simulation and further the contents between those have been different to some degree.
Specifically, a manufacturing management system was separated from a simulation system, whereby, in the case where the product was manufactured and concurrently the simulation was performed, the exclusive process flow information must individually be prepared and stored into each file.
Since the process flow preparation was troublesome and burdensome on the semiconductor technical experts, the technical experts frequently omitted the simulation.
Moreover, since the process flow information for the conventional simulations did not include peculiar data for activating manufacturing equipment, for instance information (recipe data) such as a speed of a temperature variance, gas, time, or the like at rising/falling an oxidation furnace, some differences were produced between the process flow information and the actual process results of the product.
In order to make up for absence of the recipe data, parameters of a calculating equation within the simulator have been adjusted. However, since the recipe data are different according to the equipment or the process conditions and further the variances are frequently made, it becomes necessary to adjust the parameters on all such occasions and this is ineffective. Also, such a compensating method is not attributable to the precision enhancement in the simulator itself.
Alternatively, the technical experts directly procured the recipe data of each process from a person responsible to each manufacturing line to describe the process flow for the simulation. However, the procurement of this information as occasion demands became very troublesome as works of the technical experts and the fetching of the recipe data into the process flow for the simulation become quite burdensome to the semiconductor technical experts.
In this manner, since an intermediate medium having interchangeable functions of the process flow information was provided between the manufacturing process management system and the simulator, a great deal of time was conventionally consumed to prepare a plurality of process flows by the technical experts. Moreover, since the process flow data for the simulation not including the recipe data was prepared, some problems resulted in the reliability of the characteristic precision between the simulation results and the real equipment was not obtained.
Next, the problems in the prior art in a check process of the process flow will be described.
Generally speaking, the technical experts, researchers, or computers do not necessarily prepare a correct process flow. Accordingly, the skilled experts of a process or an equipment have checked on the process flow. However, the number of the skilled experts for checking on it is short, as compared with the number of the technical experts and the researchers who prepare the process flow and the number of the process flow, and then it is the present conditions that the skilled experts cope with the check on it for a considerable time of a day (it takes about 30 min. to check on the process flow composed of 300 processes).
Moreover, the skilled experts who check on the process flow need long-termed experience and knowledge of the process and equipment, whereby the number of persons who check on it cannot readily be increased. Further, it is the present conditions that such things as the knowledge, experience, know-how of the skilled experts are not necessarily continued accurately and that these are specific to the skilled experts themselves. Further, the process flow has a tendency to be increasingly prolonged in the future and then it is expected that even the skilled experts may readily make mistakes upon checking on it.
Moreover, the process flow transfers information to a process simulator, an equipment simulator, and a configuration simulator by using specific converting means to calculate it. However, since design information (mask information) in a lithography process is short in the process flow, the technical experts selected only the information on layers which are desired to calculate it and then calculated it before and after the process flow transfers it. That is, only one-dimensional information can automatically be transferred in calculating it in the simulator.
As described above, in the case where the process flow is checked, a human being will inevitably make a mistake. Further, a great amount of time is necessary in checking the process flow. Moreover, it is expected that the number of steps in the process flow increases and that a human being positively overpasses his strength in the near future.
Moreover, since the design information (mask information) was not included in the process flow, the process flow treated only the one-dimensional information in the process and equipment configuration simulator and could not carry out the two-dimensional and three-dimensional simulations.
Moreover, in the case where the technical experts and researchers manufacture the product in multi-factory in accordance with the process flow in which the simulation or the check process is performed, they must prepare each instruction for manufacturing process conditions and each data for the manufacturing factory management which are suitable for each factory. Moreover, they must separately prepare the instruction for manufacturing process conditions and the data for the manufacturing factory management, that is two kinds of process flow data with respect to one factory.
Moreover, in the case of the manufacturing process of diversified variable-quantity, there were such drawbacks that the management process such as modifications, additions, or the like of the process flow was complicated since the codes for the conventional computer were not used for various purposes.
Moreover, when selecting the product to be phased in the manufacturing line, a production controller has conventionally judged it at his own discretion. Check items and decision data at that time were the following: that is (1) checking of a process flow data file, (2) checking of product name, (3) priority classification among different product types (4) priority classification within the product having the same kind, (5) checking of the number of allowable products in the manufacturing line to be phased in according to the priority, and (6) judging from equipments in the manufacturing line and product manufacturing progress conditions (6-1 the remaining number of products, 6-2 production capacity of the equipments, 6-3 the number of products in process in the equipment per time, and 6-4 the number of stopped products per time). When roughly classified, the check item can be classified into six items as described above, and then the production controller decides the number of products to be phased in and the phasing-in sequence based on this information.
In the above-mentioned prior art, the production controller, who decides the product to be phased in, must always check the process flow data for each product, and concurrently grasp equipment conditions in the manufacturing line or manufacturing progress conditions of the product. Therefore, accompanying enlargement in the process flow data and an increase in the kind of manufacturing equipment or the number of products to be phased in, it becomes difficult to seize correspondence of the equipment to the product manufacturing progress and presume a production planning (manufacturing progress schedule). Moreover, there are other problems in that it takes a great deal of time to judge a product decision.
In many cases in a conventional production system, the process flow information is managed as one information each kind of product, and in such a management method, it is difficult to make changes/additions/cancellations to the process flow information for each product.
Moreover, in order to decide the process conditions of a product, in particular, in the factory equipped with research development line, the processes such as product divisions for dividing the product conditions, the condition assignment, or the like is performed, and as described above, it is difficult to divide the process conditions for each product.
Moreover, the process flow information in the conventional production system is prepared according to information as represented by process codes, and the information (recipe information) for processing in the equipment corresponding to these codes also existed by the same number as the process codes. Therefore, the equipment recipe information increased together with the process conditions, whereby the recipe information management became difficult.
Moreover, in most of the conventional production systems, a process of the product, conveyance of the product, and a test of the process are performed by a human being. In particular, as a logic mechanism for deciding process sequence of the process, a human being system or a method of first processing the product which was first inputted (first-in first-out) was taken. However, taking into consideration the following process, a product balance remained in the whole factory, and therefore does not have excellent efficiency. Therefore, numerous unprocessed products remained to be processed in the equipment, and a bottleneck or the like results in the product flow.